assume cs:code
code segment
start: mov ax,cs
	   mov ds,ax
	   mov si,offset capital
	   mov ax,0
	   mov es,ax
	   mov di,200h
	   mov cx,offset capitalend-offset capital
	   cld
	   rep movsb
	   
	   mov ax,0
	   mov es,ax
	   mov word ptr es:[7ch*4],200h
	   mov word ptr es:[7ch*4+2],0
	   
	   mov ax,4c00h
	   int 21h
	   
capital:   push cx
		   push si
		   
change: mov cl,[si]
        mov ch,0
		jcxz ok
		and byte ptr [si],11011111b
		inc si
		jmp short change

ok:		pop si
		pop cx
		iret

capitalend: nop

code ends
end start
